You’ve encountered them before: The woman who opens the bathroom door with her elbow. The guy who uses wet wipes to disinfect the ATM. The cousin who won’t attend a family reunion because Great Grandma has the sniffles. Think they’re going a little too far? Maybe. Or maybe not.

While most bacteria aren’t harmful, some can be formidable adversaries for even the most robust immune systems. According to Mayo Clinic, the most effective way to keep sickness at bay is by taking action to prevent infections from occurring in the first place.

Wash your hands and towel – not air – dry.

Recent <a href="http://www.mayoclinicproceedings.org/article/S0025-6196(12)00393-X/abstract">research published by the Mayo Clinic</a> finally puts the towel versus air-dry debate to rest. The hands-down winner? Paper towels. They dry hands faster and aid in removing bacteria. Plus, used to cover the door handle when departing the privy, paper towels keep freshly washed hands free of heaven knows how much bacteria. If you’re at home, skip soaps with the ingredient triclosan, a chemical developed as a hospital surgical scrub now commonly found in a range of consumer products. Studies have shown it’s no more effective than soap and water, and may boost antibiotic resistance in some bacteria.

Hold the lemon, then hit the washroom.

A recent study found – brace yourself – <a href="http://www.pccc.edu/uploads/Xu/1x/Xu1xPvHvoXeYex8Gf1Uh0Q/JEH_Dec_07_with_Copyright.pdf">E. coli and other fecal bacteria on two-thirds of sampled restaurant lemon wedges</a>. But the most surprising restaurant germ spreader? Menus. Never let this shared card touch your silverware or plate, and be sure to wash your hands after you order.

The five-second rule is five seconds too long.

Repeatedly debunked by researchers and seventh grade science fair participants alike, the five-second rule lives somewhere between old wives’ tale and urban legend. So if that food touches the floor – or counter or sink – consider it trash.

Disinfect before you sweat.

A study in the Clinical Journal of Sports Medicine found <a href="http://journals.lww.com/cjsportsmed/Abstract/2006/01000/Prospective_Study_of_Bacterial_and_Viral.7.aspx">bacteria that cause the common cold on 63 percent of the fitness center gym equipment</a> tested. Your best bets for avoiding it? Bring your own supplies (yoga mat and towels, for instance) when possible, disinfect equipment before (for your sake) and after (for others’ sake) working out, avoid touching your face between sets and wash your hands immediately after your sweat session.

No shoes in the house. Ever.

A <a href="http://www.reuters.com/article/2008/04/22/idUS144110+22-Apr-2008+BW20080422">study by the University of Arizona</a> found that an average of 66 million microbes (including nine species of bacteria) might be crawling around the bottom of your favorite kicks. Your vacuum may make matters worse by transferring germs from contaminated surfaces to uncontaminated ones (mud room to living room). To keep those germs from migrating, spray the vacuum brush with a disinfectant after every use.

De-yuck your commute.

Gross, but true: Gas pumps are used daily by hundreds of people and are never, ever cleaned. Keep your car and immune system humming by nabbing a paper towel from the window washing station before gassing up. Use public transportation? Consider purchasing a set of non-slip antibacterial gloves to grip the subway or bus handholds without fear.

Has this ever happened to you? You are at an appointment with your doctor. She asks you for something, say, the dosage of your cholesterol medication or the results of your recent blood draw you had. You think to yourself, shoot, if only I brought that with me!